A new projection capture device has been developed to help improve the interactive user experience working with real objects and projected objects on a physical work surface. Examples of the new device are described in International Patent Applications PCT/US2011/046253 titled PROJECTION CAPTURE SYSTEM AND METHOD filed 2 Aug. 2011 and PCT/US2011/053947 titled PORTABLE PROJECTION CAPTURE DEVICE filed 29 Sep. 2011. In one implementation of the new projection capture device, a GUI (graphical user interface) is projected on to a work surface. To properly interpret touch-like user control actions in the projected GUI, it is desirable to detect when a user's finger or other control object is in close proximity to the work surface.
The same part numbers designate the same or similar parts throughout the figures.